A process for the source coding of images is already known from D. Biere "Transmission of Moving and Still Images in Highly Disturbed Narrow-band Channels Using the Radio Videophone," Bosch Technical Reports, Issue 54, 1991, page 35 et seq. In this process, an image is transmitted by means of coding of the prediction error pattern and by means of block-oriented movement estimation. Using block-oriented movement estimation, a vector field is determined, which is reprocessed using a model-based algorithm. The determined movement vectors and the corresponding contours of moving image areas are in the first instance transmitted in coded form.
In accordance with the remaining residual data rate, still deviating block contents are intraframe-coded or interframe-coded and transmitted. To determine the image areas which are intraframe-coded, the variance of the image signal within an image area is compared with a variable threshold. If the variance is smaller than the variable threshold, then the image area is intraframe-coded and transmitted. The remaining image areas are subjected to a three-stage adaptive quantization and, after a further block subdivision, structure-coded and transmitted.